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Income Taxes (Effective Tax Rate) (Details) - CAD ($) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2018 | Dec. 31, 2017
Income before provision for income taxes | $ 816 | $ 819
Statutory income tax rate | 31.00% | 31.00%
Income taxes, at statutory income tax rates | $ 253 | $ 254
Deferred income taxes on regulated income recorded as regulatory assets and regulatory liabilities | (59) | (54)
Foreign tax rate variance | (55) | 36
Amortization of deferred income tax regulatory liabilities | (37) | 0
Florida state tax apportionment adjustment | (23) | 0
Tax effect of equity earnings | 15 | 12
Financing deductions | (4) | (17)
Other | 9 | (4)
Income Tax Expense (Benefit), Total | $ 69 | $ 520
Effective Income Tax Rate Reconciliation, Percent | 8.00% | 63.00%
Income Tax Examination, Liability (Refund) Adjustment from Settlement with Taxing Authority | $ 149 |
Change in US Tax Reform [Abstract] |  |
Tax Cuts and Jobs Act, Change in Tax Rate, Deferred Tax Asset, Income Tax Expense |  | $ 1,300
Tax Cuts and Jobs Act, Change in Tax Rate, Deferred Tax Liability, Income Tax Benefit |  | 1,800
Tax Cuts and Jobs Act, Accounting Complete [true false] | true |
Receivables and other current assets | $ 1,620 | 1,326
Income Tax Reconciliation Revaluation Of US Non Regulated Deferred Income Taxes | $ 0 | $ 317
Statutory income tax rate | 31.00% | 31.00%
Deferred tax assets | $ 1,886 | $ 1,883
Regulated Operation [Member] |  |
Change in US Tax Reform [Abstract] |  |
Tax Cuts and Jobs Act, Decrease in Deferred Tax Liability due to Transition Tax |  | 1,100
Unregulated Operation Member |  |
Change in US Tax Reform [Abstract] |  |
Income Tax Reconciliation Revaluation Of US Non Regulated Deferred Income Taxes |  | $ 317

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